U.S. Pat. No. 5,805,466 (hereinafter referred to as a “document 1”) discloses an electronic device including: a pressure sensor element; power supply, output and GND terminals; and a circuit arranged therebetween. The circuit includes a signal processor, an output driver, a data storage and a calibration controller. The calibration controller includes a calibration mode detector and an I/O control.
In normal use, the signal processor receives an input signal requiring calibration from the pressure sensor element and then produces a calibrated signal through the output driver and across the output terminal.
On the other hand, when the calibration mode detector has receives a calibration mode signal, the detector disables the output driver and enables the I/O control. Once the I/O control is enabled, calibration data are allowed to be written to the data storage device across the output terminal.
The document 1 discloses a configuration that the power supply terminal is further used for a signal input. Even in this configuration, calibration data can be written to the data storage device across the output terminal.
In short, the electronic device transmits a calibrated signal to the exterior through the output terminal, and also receives calibration data through the output terminal.
Since the electronic device however employs one output terminal as an input and output terminal, it is necessary to separate an input time as the input terminal and an output time as the output terminal.